1. Field of the Invention The present invention relates to a jig or other tooling arrangement for the automatic finishing of the blades or vanes of a turbo machine. The term "blade" as used herein is intended to cover both rotary blades and also static vanes such as inlet guide vanes of turbo machines.
2. Description of the Prior Art
The manufacturing sequences for turbo machine blades which can be produced, depending upon the spheres of use, temperatures and loads applied and also depending upon the alloys used, either by forging, or by various casting procedures, generally involve machining operations or other operations of shaping by removal of material. Such operations are applied particularly to the roots and the tips of the blades to which are connected the aerofoil portions which have aerodynamic characteristics adapted to their function within the fluid flows of the turbo machine. The severe quality requirements imposed on vital parts of current turbo machines, particularly within the aeronautical sphere, lead to the provision following these conventional machining operations (milling, rectification) of finishing operations in the machined zones for example radius adjustment, de-burring and/or polishing. These operations involve a "manual" operation, requiring the personal intervention of qualified personnel and have previously been effected manually by way of a fitting operation.
Research into constant and repetitive results, into their repercussions both on the service life and duration of the life of the parts and into various performance aspects of the turbo machine relating to the balancing qualities or of the consistency in the influence on the aerodynamic disturbances, has however led to further research into automating these operations of finishing in the manufacture of turbo machine blades. Depending upon specific applications, various procedures have been considered for practical application on the basis of various different principles but these have hardly been used. In this respect reference can be made, by way of example, to electrolytic polishing operations or again, the use of moving bands or rotary brushes with the addition at the interface with the parts of various abrasive products, of various pastes or liquid suspensions. In certain cases, the results aimed at can be combined with supplementary effects (surface hardening for example) and in this category various processes for the projection of abrasives are to be found (dry sanding or moist sanding, for example).
Various disadvantages of practical operation or inadequate matching to the results sought in certain applications has lead in such cases to making use of another process of automatic deburring and radius adjustment of the blades of a turbo machine for the practical application of which tooling arrangements in accordance with the invention can be used. According to this previously proposed process, the blade is introduced into a bed formed by abrasive grains in a liquid for the deburring and radius adjustment of the end portions and this is effected in zones of the blade (root and tip) having previously been subjected to machining operations by rotating the blade within the abrasive bed. Preferably alternating rotational cycles are applied to the blade. Also preferably, the abrasive bed is constituted by moist corundum and the choice of the granular characteristics is determined as a function of the application under consideration. This kind of process has for example been applied by using corundum having a mean granular size 1590 m together with water. For applying a process of this kind, FIG. 1 of the accompanying drawings illustrates as a diagrammatic perspective view, one example of a prise art, jig or other support tooling arrangement intended for mounting of a blade and adapted at one end for mounting on a spindle or other mounting means of the machine for the introduction and for the rotation of the blade in a moist corundum bed placed in an enclosure. This tooling arrangement, comprises a hollow cylindrical body 1 carrying at one end a mounting flange 2 comprising mounting holes 3 and at the other end three parts constituting a locking mandrel, one part 4 being fixed and two others 5a and 5b cooperating with part 4. The parts of the mandrel 5a and 5b are pivotal, the pivoting being effected by two levers 6a and 6b rigid with the parts 5a and 5b and mounted on two pivots defined by clevises 7a, 7b and pins 8a, 8b. The blade 9 to be deburred is mounted on a sleeve 1a of an elastomer and which is locked between the parts of the mandrel 4, 5a and 5b. This jig has, however, various disadvantages and has led to various difficulties when in use. Blocking and frequent seizures of the pivot arrangements result from the introduction of grains or corundum, in spite of cleaning carried out after each operation and of multiple manipulations which result from it.